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2 | ni.com | NI 5922 Calibration Procedure
Introduction
The NI 5922 supports two types of calibration: self-calibration (or internal calibration) and
external calibration.
Self-Calibration
Self-calibration, also known as internal calibration, uses a software command and requires no
external connections. Self-calibration improves measurement accuracy by compensating for
variables such as temperature that may have changed since the last external calibration.
Self-calibration retains the traceability of the external calibration.
External Calibration
External calibration is generally performed with a high-precision oscilloscope calibrator at
either NI or a metrology lab. The external calibration procedure replaces all calibration constants
in the EEPROM and is equivalent to a factory calibration at NI. Because the external calibration
procedure changes all EEPROM constants, it invalidates the original calibration certificate. If an
external calibration is done with a traceable signal generator source, a new calibration certificate
can be issued.
Calibration Intervals
Self-calibration can be performed as necessary to compensate for environmental changes.
Caution
Although you can use self-calibration repeatedly, self-calibrating the
NI 5922 more than a few times a day may cause excessive wear on the relays
over time.
The measurement accuracy requirements of your application determine how often you should
externally calibrate the NI 5922. NI recommends that you perform a complete external
calibration at least once every two years. You can shorten this interval based on the accuracy
demands of your application or the requirements of your processes. Refer to the
External
Calibration Options section for more information.
Software and Documentation
Calibrating the NI 5922 requires installing NI-SCOPE version 2.8 or later on the calibration
system. You can download NI-SCOPE from
ni.com/downloads
. NI-SCOPE supports
programming the self-calibration procedures in a number of programming languages. However,
only LabVIEW and C are supported for the external calibration procedures.
NI-SCOPE 2.8 or later includes all the functions and attributes necessary for calibrating the
NI 5922. For LabWindows
™ /CVI ™ , the NI-SCOPE function panel,
niScopeCalfp
, provides
further help on the functions available in CVI. LabVIEW support is installed in
niScopeCal.llb
, and all calibration functions appear in the function palette. Refer to Table 1
for file locations.